Dynamically-switched power converter

Details Dynamically-switched power converter Dynamically-switched power converter

2002-04-12

2003-11-11

Tibbits, Pia (Department: 2838)

Electricity: battery or capacitor charging or discharging

Cell or battery charger structure

C320S166000, C363S049000

Reexamination Certificate

active

06646415

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to DC/DC power supply controllers, and more particularly to regulated capacitive-only or capacitive/inductive power converters for integrated power management systems.
BACKGROUND OF THE INVENTION
Advances in electronics technology have enabled the design and cost-effective fabrication of portable electronic devices. Thus, usage of portable electronic devices continues to increase as do the number and types of products. Examples of the broad spectrum of portable electronic devices include pagers, cellular telephones, music players, calculators, laptop computers, and personal digital assistants, as well as others.
The electronics in a portable electronic device generally require direct current (DC) electrical power. Typically, one or more batteries are used as an energy source to provide this DC electrical power. Ideally, the energy source, such as consumer batteries of standard sizes such as AAA, AA, A, C, D and prismatic 9V, would be perfectly matched to the energy requirements of the portable electronic device. Improvements in electrochemical formulations, such as alkaline and lithium electrochemical cells, have satisfied to a limited degree needs for batteries having increased shelf life, increased stored charge, and peak capacity. With even these changes, a number of deficiencies exist.
For instance, many portable devices include integrated circuits having a minimum voltage level in order to operate. Voltaic cells such as electrochemical cells have an output voltage level that generally declines over the service life of the battery. Generally, a significant portion of the battery service life occurs after the output voltage of the battery has declined below the minimum voltage level of the device. In some instances, the wasted service life is as much as 80%.
In addition, most often the voltage and current from the batteries are unsuitable for directly powering the electronics of the portable electronic device. For example, the voltage level determined from the batteries may differ from the voltage level required by the device electronically. In addition, some portions of the electronics may operate at a different voltage level than other portions, thereby requiring different energy source voltage levels. Still further, batteries are often unable to respond quickly to rapid fluctuations in current demand by a device.
A typical arrangement is shown in
FIG. 1
for a portable electronic device
10
that includes an energy source
12
, such as one or more batteries, and a load device
14
, such as the internal electronics that require electrical power. Interposed between the energy source
12
and the load device
14
is a power supply
16
that may perform a number of functions. For example, a power converter
20
, depicted as integral to the power supply
16
, provides the necessary changes to the power from the energy source
12
to make it suitable for the load device
14
.
With respect to the types of power conversion required, the power converter
20
may “step up” (i.e., boost) or “step down” the voltage. That is, the converter
20
may increase or decrease an input voltage V
S
from the energy source
12
across a pair of input terminals
24
,
25
to an output voltage V
O
provided to the load device
14
across a pair of output terminals
26
,
27
. The power converter
20
may also store an amount of energy to satisfy a brief spike or increase in demand by the load device
14
that the energy source
12
is unable to provide.
The power converter
20
may also regulate the output voltage V
O
, keeping it close to the desired output voltage level and reducing rapid fluctuations that may cause detrimental noise or cause undesirable performance of the load device
14
. Such fluctuations may occur due to changes in demand by the load, induced noise from external electromagnetic sources, characteristics of the energy source
12
, and/or noise from other components in the power supply
16
.
Conventionally, switching power converters
20
are used in portable devices due to their suitable size and cost. However, capacitive-only charge pump or inductive/capacitive switching power converters
20
typically rely upon oscillatory switching between a charge and discharge state to transfer power from an energy source such as an electrochemical voltaic cell
12
to a load device
14
. Each switching of state incurs a significant consumption of power that reduces the shelf-life of the voltaic cell.
In addition, although generally suitable for being portable, such power converters
20
still adversely impact the size, weight and cost of the portable device.
Moreover, the power converters typically cannot be optimized for a wide array of available types of electrochemical voltaic cells
12
(e.g., lithium, alkaline). Consequently, such power converters
20
generally only regulated voltage at a consider loss of efficiency or boost the voltage derived from the cell
12
in an unregulated fashion.
Consequently, a significant need exists for a power converter that more efficiently provides an efficient, regulated output voltage for portable electronic devices.
SUMMARY OF THE INVENTION
The invention overcomes the above-noted and other deficiencies of the prior art by providing an apparatus and method for a dynamically controlled inductive DC/DC power converter that efficiently transfers power from an energy source as demanded by a load device.
The present invention meets these and other needs by providing a battery with a built-in, dynamically-switched capacitive device. More particularly, a power converter is provided to adjust an output voltage (V
O
) across a positive and negative terminal of the battery dynamically based on the electrical load using an efficient switching approach, with both the power converter and switching approach optimized for incorporation within a battery container. Furthermore, the power converter would be adaptable to a number of battery types.
In some of our previous inventions, introduction of electronic circuitry within the container of a battery, especially standard-sized consumer batteries, was shown to provide a number of advantages such as by regulating the output voltage. Specifically, the following co-pending and commonly owned applications were all filed on Apr. 2, 1998: U.S. Ser. No. 09/054,192, entitled PRIMARY BATTERY HAVING A BUILT-IN CONTROLLER TO EXTEND BATTERY RUN TIME, naming Vladimir Gartstein and Dragan D. Nebrigic; U.S. Ser. No. 09/054,191, entitled BATTERY HAVING A BUILT-IN CONTROLLER TO EXTEND BATTERY SERVICE RUN TIME naming Vladimir Gartstein and Dragan D. Nebrigic; U.S. Ser. No. 09/054,087, ENTITLED BATTERY HAVING A BUILT-IN CONTROLLER, naming Vladimir Gartstein and Dragan D. Nebrigic; and U.S. Provisional Application Serial No. 60/080,427, entitled BATTERY HAVING A BUILT-IN CONTROLLER TO EXTEND BATTERY SERVICE RUN TIME, naming Dragan D. Nebrigic and Vladimir Gartstein. All of the aforementioned applications are hereby incorporated by reference in their entirety.
In another of our inventions, we showed the advantage of incorporating electronic circuitry for additional advantages such as providing enhanced indications of the state of charge of the battery. Specifically, the co-pending and commonly owned application filed on Apr. 23, 1999: U.S. Ser. No. 09/298,804, entitled BATTERY HAVING A BUILT-IN INDICATOR, naming Dragan D. Nebrigic and Vladimir Gartstein, wherein the aforementioned application is hereby incorporated by reference in its entirety. Also discussed was an inductive-capacitive power converter that advantageously increased the battery output voltage.
We have since discovered that a capacitance-only power converter based upon a charge pump had a number of desirable attributes for applications requiring the increase in battery output voltage, especially for the versions described below which provide for size and power requirements of a battery.
Furthermore, in an illustrative version, the power converter utilizes a load capacitor that receives a transfer of charge from a f

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